A plate cylinder is described in DE-C 2,523,580 having two leaves, namely an elastic leaf intended to press in a second end region on an anterior end fold of the printing plate, which is fastened to the edge of a slit in the plate cylinder, and one rigid leaf, the second end region of which serves to fasten a posterior end fold of the printing plate. These leaves immobilize the printing plate under tension, in the wound state on the external surface of a plate cylinder, and are mounted on the same tension bar.
Via their first end regions, the two leaves of this known device are bolted onto the tension bar, which is mounted so that it can pivot about a given longitudinal axis inside a bore to pass from one to the other of its limiting orientations, one of which corresponds for both leaves to a release of the end fold respectively associated with the printing plate and the other of which corresponds for both leaves to an interaction with the respective end fold for the purpose of immobilizing the printing plate in the tensioned state over the external surface of the plate cylinder.
This known device exhibits a significant drawback in that, although the mounting of the two leaves on the tension bar allows them to be dismantled when they are damaged, then allows replacement leaves to be mounted back again, these dismantling and remounting operations require the tension bar to be extracted longitudinally from the bore.
This is a complex and lengthy operation requiring a long stoppage time of the printing press and a great deal of attention, owing to the fact that this dismantling requires not only at least partial dismantling of the driving means of the tension bar, but also dismantling of numerous other components of the printing press, which are longitudinally juxtaposed with the plate cylinder and which consequently constitute obstacles to the extraction of the tension bar; naturally the components thus dismantled must then be remounted.
Furthermore, the extraction and insertion of the tension bar via a longitudinal displacement of the latter require sufficient space to be available beside the printing press, which dictates the installation of the latter in a location and prevents it from being installed in locations which, while being sufficiently large to receive it, would not make it possible to have available next to it, that is to say in the longitudinal extension of the plate cylinder, an additional dimension essentially corresponding to the longitudinal dimension of this plate cylinder.